This invention relates to the design of tweezers, and more specifically to tweezers used for orthodontic work such as the placement of braces on teeth. Tweezers in accordance with the prior art are generally cumbersome and inadequate for use in such precise work, as the brace that must be attached to the patient's tooth is often quite small in comparison to the head or gripping area of the usual tweezers, and the brace must be held securely. In addition, tweezers in accordance with the prior art are not able to properly hold an orthodontic brace, as will be described below.
The tweezers in accordance with this invention generally comprise a cross-over type tweezers with gripper jaws at one end, with the gripper jaws formed to securely hold orthodontic braces parallel to the main axis of the tweezers. While the invention disclosed herein relates to tweezers designed specifically for use by an orthodontist in affixing braces to a patient's tooth, the tweezers could be used for other means.
Tweezers in accordance with the prior art generally are either of the crossover or pretensioned type, or the non-tensioned type. A non-tensioned tweezer has a gripping jaw which is not normally in the closed position, but rather must be closed by its user. The cross-over type, on the other hand, has a gripping jaw which is held in the closed position by tension formed into the tweezer's members by the shape of the tweezer. The user must apply pressure to the members to open the jaw, align the object upon which the tweezer is to be used with the gripping area, and then reduce the pressure on the members so that the object is held by the gripping area.
This cross-over type of tweezer is preferred over other designs for work requiring the object to be held securely and accurately, as the amount of force used to hold the object does not depend on the amount of pressure applied by the user, as it is in the previous design. This is especially crucial in the orthodontics field and in the placement of braces on the patient's teeth, because such braces are very small and must be held securely and located precisely. Orthodontic tweezers are used to hold the brace to the tooth until it can be secured thereto; thus it is essential that the orthodontist be able to maintain the brace securely in the gripping area of the tweezers. Therefore, the preferred embodiment of the tweezers in accordance with this invention use the cross-over design. However, this invention is not limited to such a tweezer, and could also embody a tweezer with arms that do not cross over one another.
There are two types of orthodontic braces relevant to this invention. The first is an anterior brace, designed for attachment to front teeth and comprising a center section, and wings at one end thereof. The opposite end of the center section is attached to the patient's tooth, and the slot receives and holds the wires that are used to connect the braces on adjacent teeth. The second type of brace is a posterior brace, designed for attachment to back teeth and comprising a center section, wings at one end thereof, and a base at the opposite end thereof. The base is slightly larger than the center section, and is concave to conform to the surface of the patient's tooth. A brace is glued to the patient's tooth, and it is crucial that this glue stays on the center section of an anterior brace, or the base of a posterior brace, and does not move up on to the wings. Glue under or on the wings prevents successful placement of the wires through the braces, and thus requires the removal of the brace.
However, current designs of cross-over type tweezers do not provide a gripping head that is adequate to securely hold an orthodontic brace and prevent glue from being accidentally placed on the wings. For example, U.S. Pat. No. 2,595,683, issued to Lo Monte, discloses a cross-over type tweezer using a means to adjust the tension between the arms. While this tweezer is useful for delicate work in picking up small objects, the head of the tweezer therein disclosed is not adequate for holding braces. Specifically, the long, narrow head of the Lo Monte tweezer, and tweezers similar to it, requires the orthodontist to hold the brace by the wings as he or she is attaching the brace to the tooth. Thus, there is nothing to prevent excess glue from contacting the wings. To overcome the flaws of earlier tweezer designs, the present invention contains a head with a gripping area that is transverse the axis of the tweezers and is formed to securely grip and hold a brace on the center section and behind the wings. Therefore, the center section or base may be glued to the tooth, and the gripping jaw of the tweezers actually blocks the flow of any excess glue from the tooth to the wings.
In addition, the wide and flat shape of the gripper jaws hold the brace more securely than do other designs of tweezers such as the Lo Monte tweezer described above, which generally have a gripping surface which is elongated along the same axis as the main body of the tweezers. These and further features of the preferred embodiment of this invention will be given in detail below.